"Our study is the first to address whether oral anticholinergic medications affect the risk of pneumonia in older people," senior author Dr. Sascha Dublin, an associate investigator at the Seattle-based Group Health Research Institute, said in an institute news release.

"This is important because so many older people use these medications, and pneumonia is such a common cause of illness and death in this age group," Dublin explained.

Researchers looked at more than 1,000 patients with pneumonia, aged 65 to 94, and a group of more than 2,000 people matched for age and sex without pneumonia.

"We found a link between both acute and chronic use of anticholinergic medications, and a much higher risk for developing pneumonia," study first author Dr. Kathleen Paul, a third-year resident in family medicine at Group Health, said in the news release.

Acute use was filling at least one prescription for an anticholinergic medication within 90 days before being diagnosed with pneumonia, the study authors explained. Chronic use was filling at least three prescriptions within the year before diagnosis.

"It isn't clear why anticholinergic medications might raise pneumonia risk, but one possibility is that by causing sedation and altered mental status, they raise the risk for breathing problems -- and lung infections," Paul said in the news release. "But more research is needed," she added.

The study only found an association between the drugs' use and pneumonia, not a direct cause-and-effect relationship.

The findings were published March 2 in the Journal of the American Geriatrics Society.

In some cases, other drugs can be prescribed instead of anticholinergics, Paul noted.

More information

The U.S. National Heart, Lung, and Blood Institute has more about pneumonia.